Term | Definition |
compund | is a distinct substance that is composed of the atoms of two or more elements and always contains exactly the same relative masses of those elements |
chemical formula | the types of atoms and the number of each type in each unit (molecule) of a given compound are conveniently expressed |
elements symbol | abbreviations of elements |
law of constant compsition | that a given compound always has the same composition, regardless of where it comes from |
electrons | negative particles |
nuclear atom | an atom with a dense center of positive charge around which tiny electrons moved in a space that was otherwise |
.proton | has the same magnitude (size) of charge as the electron, but its charge is positive |
neutron | is slightly more massive then a proton. It has no charge |
isotopes | atoms with the same number of protons but different numbers of neutrons |
atomic number | number of neutrons and the number of atoms |
mass number | the sum of the number of neutrons and the number of protons in a given nucleus |
periodic table | list of elements that increase by atomic number |
groups | families of elements with similar chemical properties that lie in the same vertical column on the periodic table |
alkaline metals | first column of elements (group 1) |
alkaline earth metals | Group 2 elements |
halogens | group 7 elements |
noble gases | group 8 elements |
transition metals | large collection of elements that spans many vertical columns |
most elements are | metals |
physical properties of metals | efficient conduction of heat and elctricity
malleability
ductility
a lustrous appearance |
malleability | can be hammered into thin sheets |
ductility | can be pulled into wires |
lustrous | shiny |
nonmetals | relatively small number of elements that appear in the upper right corner of the periodic table |
metalloids | elements that show a mixture of metallic and nonmetallic properties |
diatomic molecules | molecules made up of of two atoms |
allotropes | different forms of a given element |
buckminstrefullerene | three allotropes of carbon are the familiar and graphite forms plus a form that has only recently discovered |